Active Photonic Crystal Nano-architectures

The development of nano-scaled photonic crystal structures has resulted in many new devices exhibiting non-classical optical behavior. Typically, in these structures a photonic band gap and associated defect mode are used to create waveguides, resonators, couplers and filters. In this paper we propose that the functionality of these structures can be significantly enhanced by the infiltration of the photonic crystal with other classes of materials, particularly highly nonlinear liquid crystals and electro-optical materials. The properties of conventional 2D PC slab waveguides were simulated by the finite difference time domain method and shown to exhibit very large refraction and dispersion, and significant tunable effects under bias when infiltrated with liquid crystal. In particular, a new superlattice photonic crystal concept is proposed and shown to exhibit up to ∼ 50 tunability in the angle of refraction when alternate liquid crystal infiltrated pixel rows were modulated from their aligned to unaligned state. This modulation corresponds to index changes from 1.5 to 2.1; it is assumed that a refractive index change of up to approximately ∆n = 0.6 can be achieved. The superlattice effect was also demonstrated to induce new switching and out-coupling effects that were strongly dependent on the direction of propagation and index modulation. These simulations demonstrate the potential of a new class of optically-active photonic crystal architectures to tune giant refraction and dispersion characteristics and to enable new switching phenomena.